In general, a radiation beam intensity modulator is a device for modulating a dose distribution of a radiation beam by being placed in a center of radiation beam or in contact with or inserted into a body of a patient.
A radiation beam intensity modulator is used to increase a tumor radiation dose and to protect surrounding normal tissues by modulating an intensity of a radiation beam in radiotherapy. The radiation beam intensity modulator is used for electron beam, X-ray, proton, and particle beam radiotherapies, and in particular, the radiation beam intensity modulator is essential in order to obtain a radiation dose distribution suitable for the shape of a tumor, in a case of the proton and particle beam radiotherapy.
In addition, the radiation beam intensity modulator is used to improve quality of an image through an enhanced beam quality when an image is obtained using radiation, because it is effective in irradiating a radiation beam to a desired region by adjusting an intensity of a specific region or blocking the radiation.
Recently, proton and particle beam radiotherapy facilities have been rapidly increased worldwide, and since the National Health Insurance has started to cover intensity modulated radiotherapy in Korea, a technique for intensity modulated through simple processes has been necessary.
However, according to a conventional intensity modulated radiotherapy, radiation is entirely or partially shielded by using a radiation collimator to obtain desired intensity modulated radiation or a modulator made by cutting using milling may be used.
The former has a possibility of generating an error due to malfunction of the collimator, it is difficult to calculate a scattered dose occurring in collimator gaps or leaves, and may increase a duration of treatment and uncertainty during the radiotherapy of moving organs.
Although the latter is free from the above disadvantages, it is difficult to be used in medical facilities due to severe noise from cutting process, generation of contaminated coolant water, need for a wide space to accommodate cutting facilities, and the difficulty of high-precision processing.